Recently, a flat display panel, in particular, a liquid crystal display, is widely used.
Generally, unlike a conventional cathode ray tube (CRT), the liquid crystal display (LCD) may require a back light module that provides light uniformly to an entire screen.
FIG. 1 is a perspective view of deal drawing illustrating a back light module of related art.
As shown in FIG. 1, in the back light module of related art, a lamp 1 which is a linear light source and a lamp reflecting plate that reflects light of the lamp 1 may be disposed in a side of a light guide plate 2 that converts the light from the lamp 1 into a surface light source, and a reflection sheet 3 to prevent a light leakage may be disposed in a lower portion of the light guide plate 2.
In addition, a diffusion sheet 4 to uniformly diffuse light may be disposed in an upper portion of the light guide plate 2, and a prism sheet unit 5 that has a plurality of linear prisms of triangle shape protruded in an upward direction to concentrate the diffused light may be placed on the diffusion sheet 4. The prism sheet unit 5 in which the plurality of linear prisms are arranged may concentrate light, and a protection sheet 6 to prevent a defect such as a scratch of the prism or an impaction of foreign substance may be disposed in an upper portion of the prism sheet unit 5.
In addition, as shown in FIG. 2, the prism sheet unit 5 may be configured of two sheets of a first prism sheet 51 and a second prism sheet 52. A plurality of prisms 53 may be arranged in parallel on one surface of the first prism sheet 51, and a plurality of prisms 54 may be arranged on one surface of the second prism sheet 52 in a perpendicular direction to the prisms 53 of the first prism sheet 51 so that light in a different direction may be concentrated to enhance a light collection efficiency.
However, as shown in FIG. 1, in the back light module of related art, since two prism sheets 51, 52 and the diffusion sheet 4 are provided as a separate product, each sheet should be assembled in a separate frame or housing when it is assembled.
Accordingly, a man hour may be increased, and a possibility of generation of assembly defect may be increased as the man hour is increased. In addition, as a gap is generated between the two prism sheets and the diffusion sheet, a total thickness may be increased.